Electric motor construction

• US 3,898,488 A
• Filed: 02/04/1974
• Issued: 08/05/1975
• Est. Priority Date: 02/28/1972
• Status: Expired due to Term

• Current Assignee: Emerson Electric Company
• Original Assignee: Benjamin F. Chestnut, Bill G. Kilmer, Richard H. Weber, Robert D. Erwin
• Inventors: Erwin, Robert D., Weber, Richard H., Kilmer, Bill G., Chestnut, Benjamin F.
• Primary Examiner(s): Duggan, Donovan F.
• Application Number:
  US05/439,461
• Time in Patent Office: 547 Days
• Field of Search: 310/41,162-164,156,172,83
• US Class Current: 310/83
• CPC Class Codes: G04C 15/00 Clocks driven by synchronous motors
• CPC Class Codes: H02K 1/12 Stationary parts of the magnetic circuit
• CPC Class Codes: H02K 7/116 with gears
• CPC Class Codes: H02K 7/1185 with a mechanical one-way direction control, i.e. with means for reversing the direction of rotation of the rotor

Abstract

A U-shaped outer field plate is inverted over a rectangular mounting plate to form an enclosure linearly extending to an area near the center of the mounting plate. The enclosure provides a space for an energizing winding, an inner field plate, and a permanent magnet rotor. At least one shaft extends from the mounting plate juxtaposition the enclosure and carries at least one gear for a speed reduction means. The poles of the motor are asymmetrically arranged to provide good motor starting characteristics without substantial loss of running torque.

Claims

1. An electric motor construction comprising:

a. a substantially rectangular mounting plate, b. a U-shaped outer field plate having a substantially flat bottom portion and upstanding legs extending therefrom, said Ushaped outer field plate disposed over said mounting plate to provide an enclosure linearly extending to an area near the center of said mounting plate, an aperture disposed in said flat-bottom portion, and poles provided in said U-shaped outer field plate extending into said aperture, c. an energizing winding carried by said mounting plate within said enclosure, d. an inner field plate disposed above said energizing winding having poles intermeshing said poles of said U-shaped outer field plate, e. a permanent magnet rotor disposed above said energizing winding and rotatable within said intermeshed poles and having a plurality of magnetic poles along its periphery, f. at least one shaft extending from said mounting plate juxtaposition said enclosure, g. a speed reduction means including at least one gear rotatably journalled on said shaft, h. an arm extending from said inner field plate and a notch in a distal end of said arm at least partially surrounding said shaft so as to provide a means for locating the center distance between said gear and said rotor, and i. means operably connecting said rotor with said speed reduction gear.

2. An electric motor construction according to claim 1 wherein said energizing winding includes an iron core, a bobbin surrounding said core, and a coil carried by said bobbin.

3. An electric motor construction according to claim 2 wherein said bobbin includes means to locate said outer and inner field plates.

4. An electric motor construction according to claim 3, wherein said locating means includes at least one channel protruding from said bobbin extending adjacent to said outer and inner field plates.

5. An electric motor construction according to claim 1, further including one-way directional means to prevent a continued wrong-way directional rotation of said rotor.

6. An electric motor construction according to claim 1, wherein said speed reducing means includes four reduction stages.

7. An electric motor construction according to claim 6, wherein said four stages includes a first stage gear and pinion rotatably carried on said shaft, a second stage gear and pinion rotatably carried on a second shaft rotatably journalled to said mounting plate, a third stage gear and pinion rotatably journalled on a third shaft, and a fourth stage gear fixedly coupled to said second shaft.

8. An electric motor construction according to claim 7 wherein the center distance between said first stage gear and pinion and said third stage gear and pinion is substantially the same as the center distance between said first stage gear and pinion and said fourth stage gear.

9. An electric motor construction according to claim 1, further including a shroud substantially enclosing said field plates, said permanent magnet rotor, said energizing windiNg, and said speed reducing means.